1. Field of the Invention
The present invention relates to question answering technology, and more particularly, to a natural language question answering system and method, and a paraphrase module capable of detecting an answer to a user's question.
2. Discussion of Related Art
Natural language question answering technology is technology of analyzing a user's question, searching for answers suitable for an intension of the question in various contents, extracting the answer among them, and providing the extracted answer to the user.
Together with the advent of a mobile era, the natural language question answering technology has been again spotlighted in order to overcome a hardware limitation (a limitation of search result display due to a small screen) of a mobile device.
While suggesting technology named “siri” for the iPhone, technology of asking a question with a user's voice and answering to the question had been introduced.
Conventional natural language question answering technology includes a question analysis operation of analyzing a user's question, a document search operation of searching for related content, an answering extraction operation of extracting an answer in the searched document, and an answer suggestion operation of suggesting the extracted answer.
The conventional natural language question answering technology is a method of searching for a sentence or a paragraph having the same sentence structure and word as the question based on data redundancy of big data, and finding an candidate answer in a corresponding sentence or paragraph.
Basically, the method is based on an assumption that the content having the same sentence structure and word as the user's question exists anywhere on a widespread Web. However, this approach method is based on the big data named the Web, and a filtering on false information which is a disadvantage of the Web is prerequisite for the approach method.
Also, the conventional natural language question answering may be performed based on limited content having high reliability such as an encyclopedia, a Wikipedia dictionary, a Korean dictionary, etc., but in this case, since there is a limitation of searching for the sentence and the paragraph including the answer, a recall ratio and accuracy may become lowered.